Macaques living near a Buddhist shrine in Lopburi, Thailand, are known to pull out hair from visitors to use as floss.
Worshipers see the monkeys as divine servants, the researchers said, which helps explain why people let the macaques pull out their hair.
About 50 of these monkeys have been seen jerking strands of hair back and forth between their teeth. Similar behavior has been seen before using coconut fibers or twigs.
Source: National Geographic – read the whole story here.